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When the power goes out, the clock starts ticking on everything in your fridge and freezer. A fall storm, a downed line, a grid emergency — however the outage happens, you’re often left guessing: Is this still good? Do I need to toss it? And no, a simple sniff test does not tell you what you need to know.

I spoke with two food safety experts about how long your food actually stays safe once the power fails, the signs it’s time to throw something out, and the simple steps that can help save your perishables the next time your power goes down.

How long does food stay safe in the fridge and freezer after a power outage?

First, to state the obvious, you don’t have to worry about non-perishable food in your pantry. When the power goes out, you really only need to think about perishable stuff in your fridge and freezer. The good news: “A refrigerator will keep food cold for about four hours if it is unopened,” says Dr. Vanessa Coffman, alliance director for Stop Foodborne Illness. “A full freezer will keep the temperature for approximately 48 hours, or 24 hours if it is half full, but only if the door remains closed.”

In other words, a well-stocked freezer buys you significantly more time than a fridge — but only if you can hold off on opening it. Both experts I spoke with agreed that this tactic of keeping your fridge and freezer shut is key.

“The most important thing you can do is keep your refrigerator and freezer doors closed as much as possible,” says Melissa Vaccaro, senior food safety program specialist at the National Environmental Health Association. “Every time you open the door, cold air escapes and the temperature inside rises more quickly.” That means you should resist the urge to peek inside and check on things — each open door lets precious cold air out and speeds up the clock on your food’s expiration.

How can you tell if food should be thrown out after a power outage?

It’s tempting to trust your senses — for example, sniffing for a bad odor or examining food to see if it “looks bad” — but experts say that’s the wrong approach. “One of the most important things for consumers to understand is that you cannot reliably determine whether food is safe by looking at it, smelling it, or tasting it,” Vaccaro says. “Food can contain disease-causing microorganisms without looking or smelling spoiled. And never taste questionable food to decide whether it is safe.”

Food that looks, smells, and even tastes normal can still make you sick, so don’t let your gut be the judge. Think about it, do you really want to be dealing with food poisoning during a power outage?

Instead, the only tried-and-true test is time. “Again, an unopened refrigerator will generally keep food cold for about four hours,” Coffman says. But once your fridge climbs back up to room temperature, the countdown gets much shorter. “Perishable foods such as milk, cheese, meat, poultry, seafood, and leftovers should not be left at room temperature for more than two hours,” Coffman says. “If they have been at room temperature for longer than two hours, they should be discarded.”

When the power comes back on, your freezer requires its own check. “Use time and temperature. After power is restored, check the temperatures in the refrigerator and freezer,” Vaccaro says. “If an appliance thermometer in the freezer reads 40 degrees Fahrenheit or below, the food may be refrozen. If no thermometer was present, check individual frozen packages. Food that still contains ice crystals or is 40 degrees Fahrenheit or below can generally be refrozen or cooked.”

No thermometer, no ice crystals, and a temperature above 40 degrees Fahrenheit, though, means it’s better to toss it than risk it. Keeping appliance thermometers in your fridge and freezer can be a helpful way to monitor whether food is safe or not (more on that below).

Which products help you keep your food fresh during a power outage?

Based on what food safety experts recommend having on hand, I rounded up products designed to help keep your fridge and freezer contents cold during an outage — from appliance thermometers to coolers and ice packs. Every item below has a 4-star average rating or higher from 1,000 or more shoppers.

Both experts recommend keeping an appliance thermometer in your fridge and freezer at all times, so you can accurately monitor temperatures if the power goes out. This set comes with two thermometers that cover a range of -20 degrees Fahrenheit to 80 degrees Fahrenheit, with an easy-to-read safety indicator, making it simple to check whether your food is still within a safe temperature zone.

During an extended outage, a rolling cooler can double as a practical “access cooler” for the items you reach for most, says Vaccaro. The Coleman Classic Series Portable Rolling Cooler has a sturdy, insulated design with wheels and a retractable handle, making it easy to move and keep near your kitchen.

“Move items such as milk, lunch meat, yogurt, and other perishable foods that require refrigeration for safety into a cooler with enough ice or frozen gel packs to keep them at 40 degrees Fahrenheit or below,” says Vaccaro. “This allows you to use those foods without repeatedly opening the refrigerator and losing cold air.”

These reusable ice packs lay relatively flat and can be tucked into a cooler alongside perishables like milk or deli meat to keep items at a safe temperature during an outage, or store them in your freezer year-round, nestled between frozen foods, so they’re ready to help maintain a safe temperature the moment the power goes out.

Say the power goes out in the middle of the night. You may not notice and then could wake to a fridge full of potentially spoiled food. This device plugs directly into an outlet and monitors your refrigerator, freezer, or other essential appliances. If the power goes out, it alerts you with a loud sound and flashing LED light, then continues alerting for up to 12 hours — giving you a chance to act before your food goes bad.

The Anker Solix S2000 is pricey, but it could save your groceries and charge devices and other appliances when the power goes out. It can run a standard refrigerator for more than 30 hours on a full charge, and it recharges from a wall outlet or solar panels, according to Anker. If you live in an area (like a hurricane zone) that gets hit with a lot of power outages, it may be worth the investment.

Is there anything you can do before a power outage to keep food from spoiling?

“If you know in advance that severe weather or another event may cause a power outage, prepare before the power goes out,” Vaccaro says. “Keep appliance thermometers in both the refrigerator and freezer and freeze containers of water or gel packs so you can move stuff to a cooler if needed.” The Food and Drug Administration (FDA) also recommends freezing refrigerated foods you may not need immediately, such as leftovers, milk, and fresh meat or poultry, and grouping frozen foods together so they stay cold longer.

If you know the outage is going to stretch on, it may be worth investing in extra cold power. “If you know the power will be out for a prolonged period of time, buy dry or block ice to keep the refrigerator as cold as possible,” Coffman says. “Fifty pounds of dry ice should keep an 18 cubic foot, fully stocked freezer cold for two days.” That kind of buffer can be the difference between saving a freezer full of groceries and losing everything in it.

Still, even with the best preparation, some judgment calls are unavoidable — and experts say it’s always better to be cautious. “When in doubt, throw it out,” Coffman says. “Eating food that has been held at unsafe temperatures can increase the risk of foodborne illness.” No amount of prep work is worth the risk of getting sick, so when you’re not sure, the safest move is always to let it go.

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Meet our food safety experts

At NBC Selected, we work with experts with specialized knowledge and authority based on relevant training and/or experience. We also ensure all expert advice and recommendations are made independently and without undisclosed financial conflicts of interest.

• Melissa Vaccaro is a senior food safety program specialist at the National Environmental Health Association
• Dr. Vanessa Coffman is the alliance director for Stop Foodborne Illness.

Why trust NBC Selected?

I am a commerce editor at NBC Selected and a journalist who regularly covers wellness, beauty, home and lifestyle. I have written about cyclosporiasis, the best mini fridges and more. For this story, I spoke with two food safety experts about how to keep perishable food fresh during a power outage.

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